Those fans, after all, apparently fully understand the banality attached to Celtic’s place in Scottish football. For virtually every Celtic home league match of last season, thousands of empty seats provided the backdrop. Season tickets had been purchased as a means of helping the club, but without the excitement of a title race worthy of that name, supporters have little incentive to turn up.

Celtic’s hierarchy will bear precisely that in mind when looking for Lennon’s replacement, rendering a box-office appointment entirely feasible. Henrik Larsson’s name has been touted heavily already, albeit there would be a clear risk on both sides.

When Lennon took over Celtic, firstly on a caretaker basis in March 2010, the club was a rudderless ship after Tony Mowbray’s disastrous spell in charge. Lennon has taken the club on a successful journey since then, a journey he now believes can go no further on existing resources. Along that road, Lennon proved himself not only a better manager but a more thoughtful and erudite personality than his many detractors had given him credit for.

The board did not rush to appoint Lennon permanently and were in a strong bargaining position given the former Celtic captain’s desire to take the job. Mowbray, and Gordon Strachan before him, took the Celtic post on far more lucrative terms than Lennon.

The intervening years have seen Lennon claim three league championships and two Scottish Cups. There have been occasional frustrations and let-downs, along with the recurring sense that the manager did not have the all-encompassing control of Celtic that he would have relished.

Yet Lennon has always held such a strong affinity not only for Celtic but for Glasgow which renders this decision easily the toughest of his career. It was entirely possible that he could have left Celtic a year ago but instead decided to stay on for the ultimately successful challenge of progression to the Champions League proper.

And, of course, he stayed on because he had such a strong alliance with what is a stable club. During his Celtic tenure, Lennon was never offered a job elsewhere despite the routine linking of his name with posts in England. It is a myth to suggests such links always emanated from anyone associated with Lennon.

In order to negotiate that European hurdle once again, Lennon would require a boost to his squad and an appetite, which has clearly gone. Managing either half of the Old Firm is a draining business, played out in a goldfish bowl, with the landscape more curious now – on account of the demise of Rangers – than ever before. These jobs have a limited shelf life.

It is hardly unusual for someone such as Lennon to grow tired of this scene. The 42-year-old is also well aware of the dangers associated with stagnation.

Recently, there had been hints that this split would be forthcoming. In radio and television interviews, Lennon came as close as he could to admitting that the transfer ambitions of the Celtic board may not match his own.

The recent and surprise departure of Lennon’s assistant, Johan Mjallby, was portrayed as entirely of the popular Swede’s own volition. There is, though, a viable alternative story. If, as has been speculated, Mjallby’s replacement would be appointed by the board with the long-term management structure of the club in mind, that suggests that Celtic’s directors knew Lennon would not be around much longer.

Lennon is a clear thinker. By the time he met Celtic’s majority shareholder Dermot Desmond in Dublin on Monday, he knew what message he would be passing on. Desmond, inevitably, would also have known what was coming. There is no prospect of Celtic being caught off-guard by Lennon’s departure.

Lennon has no job lined up but, impressively given the calibre of out-of-work managers, backs himself to return to the game before too long. More immediately, he will form a part of the BBC’s punditry team at the World Cup.

Lennon’s legacy will be two fold. As a one-off occasion, the Champions League victory over Barcelona in November 2012 will be cherished by Celtic’s supporters for a long time to come. The result generated a level of positive publicity for Lennon and his players that would never be achievable from any amount of success in Scotland.

More practically, the riches Lennon earned the club through consecutive seasons in the Champions League and the development, and sale, of players placed Celtic in a position of real fiscal strength. That will be endorsed once more, as and when Fraser Forster and Virgil van Dijk leave Glasgow for high fees.

Lennon’s talent for spotting and improving bargain basement talent should appeal to boards of directors in England.

Celtic, who had been such a mess before his arrival, owe Lennon a debt of gratitude for the level of improvement. There is no requirement for bad feeling on anybody’s part.